The U.S. Congress is in recess and members are scattered across the country in their home districts.

But a number of congressional leaders appeared on Sunday talk shows to voice alarm about the threat posed by the Islamic State militant group in the wake of the brutal murder of American journalist James Foley.

The Republican chairman of the House Homeland Security Committee, Michael McCaul that the Islamic State, also known as ISIS, presents the greatest threat the world has seen since the September 11th terrorist attacks of 2001.

"This has been festering for the past year, and now it is culminating with the killing and beheading of an American journalist, which I think is a turning point [for] the American people," McCaul said on ABC's This Week. "It has sort of opened their eyes to what ISIS really is."

The Republican chairman of the House Intelligence Committee, Mike Rogers, agreed. Rogers told NBC’s Meet the Press that some fighters from Europe and the United States who have gone to the Middle East to join the terrorist network could travel easily back to the West.

“They are one plane ticket away from U.S. shores and that’s why we’re so concerned about it," he said.

Retired U.S. Marine General John Allen agreed on the seriousness of the threat, and said the United States needs to take a regional approach, working with its allies.

“It's going to require a comprehensive approach," Allen said on This Week. "It's got to be more than simple pinpoint attacks on key ISIS locations that are just security locations in and around dams.”

President Obama has tried to limit the new military campaign in Iraq to protecting civilians under dire threat and American diplomats. But he also said America will be relentless and do whatever it takes to protect U.S. citizens.

Members of Congress reacted with strong emotions to the execution of James Foley, but some have cautioned that the U.S. should not be provoked into sending combat troops back into Iraq. Democratic Congresswoman Donna Edwards said Congress needs to debate any military escalation when members return in September.

"But we need to have the debate. I think that is really important," she said. "I don't think the president can continue beyond the War Powers authorization without an authorization from Congress."

Analysts say the president will likely weigh the consequences of expanding U.S. military action against the extremist group in the coming days.